1. Field of the Invention
The present invention generally relates to an image processing device for performing image drawing processing according to image drawing instructions given by a host.
2. Description of the Related Art
In the related art, in an image processing device used in a printer or the like, in response to drawing instructions given by a host computer, a CPU interprets the drawing instructions, generates bitmap data to be sent to a printer engine, and stores it in a memory. The image processing device transfers the bitmap data stored in the memory to the printer engine by DMA transfer in accordance with operation of the printer engine, and, thereby, the printer engine prints out relevant image data.
In order to improve the processing speed of the image processing device, Japanese Laid-Open Patent Application No. 11-31052, for example, discloses a document processing system which divides document data into a plurality of sets of first interim data, distributes the respective ones of the plurality of sets of first interim data into a plurality of drawing units which can operate it in parallel, and convert the plurality of sets of first interim data into a plurality of sets of second interim data. Then, a combining unit combines the plurality of sets of second interim data in page unit, so as to generate image data which can be printed out. Thus, high speed processing can be achieved.
However, Japanese Laid-Open Patent Application No. 11-31052 does not discloses a configuration with regard to a case where the interim data is data obtained through data compression. However, image data for a size of A4 in 600 dpi of 8 bits for each color of RGB has a data amount of approximately 100 MB, for example, and, as a result, when this data is transferred from a host computer to a printer without compression, a considerable time is required for the transfer. In order to solve this problem, image data is transferred commonly after being appropriately compressed.
However, if thus-compressed image data is to be processed by the above-mentioned document processing system, the compressed image data should be decompressed first, then be divided into a plurality of sets of drawing instructions and corresponding image data, which are then distributed into the plurality of drawing units. Thus, the plurality of drawing units cannot perform the processing until the decompressing processing is finished, and, thereby, it is not necessarily possible to achieve high-speed image production processing.